Am I correct in interpreting this whole thing as only a minor interuption to a preview show? Because, if so, why all the fuss?? I've seen quite a few shows in previews and I don't expect everything to run smoothly - surely that's the whole point?!

Heck, I've known preview shows not even make it through the first act (sad for those in attendance, but they have been offered replacement tickets, so they really can't complain).
The last show I saw in previews was Priscilla in London and the director made a pre-show announcement that they'd not had a single complete run-through of the show without one technical hitch or another. As it happened they got through that first show virtually unscathed and it was one of the BEST nights I've ever experienced in any theatre anywhere! (And I've seen A LOT of shows over the years).
I'm hoping my luck holds out because I'm seeng '9-5' in previews next week and I can't wait! And as others have pointed out, technical problems can halt shows LONG after their preview periods.
Seen some shows in my time....